Display panels such as of a cathode ray tube (CRT) or a flat panel display provide a video image for viewing. The display panel is generally comprised of glass and may include one or more layers of an antireflective coating on its outer surface for reducing light reflections which degrade the video image. Each layer is typically one-quarter (1/4) of the wavelength of the light to be suppressed in reflection. A common antireflective coating is comprised of a gel material, such as silica gel, and may include dopants, where the degree of crosslinking of the gel material determines the density of the material and hence its light refractive index. Increased crosslinking affords a lower light refractive index.
U.S. Pat. No. 5,254,904 discloses an arrangement employing a plurality of antireflective coating layers such as for a CRT having a light refractive index gradient such that the refractive index decreases in the direction from the display panel surface to the outer layer of the coating. The change in light refractive index between adjacent layers having the same starting composition is effected by varying the temperature, acidity and degree of hydrolysis of the starting material. This approach is overly complicated, requiring precise control of the composition of the coating, and is thus impractical for large scale manufacturing of consumer-type video display panels.
The present invention addresses the aforementioned limitations of the prior art by providing an economical method which is easily implemented and controlled using a common starting material for providing an antireflective coating having a precisely controlled light refractive index for use on a video display panel.